The invention relates to a superconducting winding having at least one HTS conductor which is at least largely in the form of a strip and is subjected to a predetermined winding tension in individual turns of the winding and which, on its outside, has an associated armoring strip composed of a material whose tensile strength is higher than that of the HTS conductor. The invention also relates to a method for production of a superconducting winding such as this. A corresponding winding and a method for its production are disclosed in JP10 92630 A.
Coil windings composed of superconductors have been provided for a very long time in the field of superconducting technology, in particular the field of high-energy and particle physics or electrical machines. In this case, in general, the conductors that are used have a traditional, metallic superconducting material with a low critical temperature Tc, so-called low-Tc superconductor material (LTS material for short). The main representatives of this material type are NbTi and Nb3Sn.
Since oxidic superconductor materials with a high critical temperature Tc have become known, the so-called high-Tc superconductor material (HTS material for short), attempts have been made to produce corresponding windings using conductors composed of these materials as well. A corresponding proposal can be found in the initially cited JP 10 92630 A. The winding which is disclosed in this document is created using HTS conductors whose HTS material is of the Bi-cuprate type, for example (Bi, Pb)2Sr2Ca2Cu3Ox or of the Y-cuprate type, for example YBa2Cu3Oy. The conductors are in this case of the so-called monocore type or multifilament type, with one or more superconducting conductor cores composed of the HTS material being embedded in a silver matrix. In order to form the winding, an initial product of the HTS conductor, in which the superconducting phase and the corresponding structure have not yet been completely formed, is wound around a winding core, together with an armoring strip composed of a silver alloy. The material of the armoring strip in this case has a greater tensile strength than that of the HTS conductor. Once the structure has been created, it is subjected to an annealing process in which the superconducting phase and the structure are formed and a metallurgical joint is created between the matrix material of the HTS conductor and the armoring strip on the common touching surface. The construction of the winding is correspondingly complex because of the requirement for an annealing process.
It is known from “Industries Atomiques”, volume 5/6, 1970, pages 33 to 46 for an armoring strip to be wound in parallel to form an NbTi superconductor in the form of a strip in order to form large magnets composed of superconducting windings using traditional (metallic) LTS material, for example for the European bubble chamber at CERN. The armoring strip may be composed of stainless steel. The superconductor that is used is in this case composed of a plurality of individual conductors, each having NbTi conductor cores embedded in a copper matrix, which are joined together by soldering to form a rigid conductor structure (cf. also DE 1 765 917 C).
Particularly for relatively large windings, for example of relatively large magnets or electrical machines, it is also intended to use HTS conductors with a higher current carrying capacity, which are of the so-called transposed-conductor type. Corresponding conductors may comprise individual conductors which are largely in the form of strips and are transposed with one another, and which are each either of the so-called monocore type or multifilament type. These are known, for example, from WO 01/59909 A1. HTS transposed conductors can also be formed using individual conductors, in the form of strips, of the coated conductor type according to WO 03/100875 A.
If one wishes to create windings using HTS transposed conductors such as these, then it is necessary to remember that, taking account of the radial thickness of the transposed conductor, the individual conductor positions have different winding radii and therefore different circumferential lengths per turn. This results in the individual conductor positions having a specific conductor length requirement. Those individual conductor positions which face the inside of a winding former therefore have a reduced conductor requirement, in comparison to the outside. During winding, this leads to compensation movements of the individual conductors, which are evident in the transposed-conductor assembly composed of the HTS individual conductors spreading out. This results in the following problems for use:                it is necessary to ensure that the transposed conductor is placed on a winding former completely by hand, in order to produce windings;        the mechanical load capacity of the winding in the tangential direction is restricted by the tensile load capacity of the HTS individual conductors.        
Taking these problems into account, when producing windings using HTS transposed conductors such as these, the contact between the conductor and the winding former can be ensured by visual inspection. However, the spreading out which occurs on the winding former must be smoothed by hand. The individual conductor lengths are compensated for after processing of a transposition length, that is to say after one complete change in the individual conductor positions. A corresponding production technique with manual actions is correspondingly complex.